Abstract: :
Purpose:We compared mRNA expression in male and female mouselacrimal glands to identify differentially expressed proteinsin tears.Methods:Poly(A)+ RNA from male and female Swiss Webster mouselacrimal glands was isolated and reverse transcribed. Differentialdisplay analysis coupled with the polymerase chain reaction(PCR) was used to identify mRNAs that were expressed at differentlevels in male and female lacrimal glands. These PCR productswere re–amplified, subcloned and sequenced. The sequenceswere compared with those in the NIH databases. Poly(A)+ RNAsfrom several mouse tissues (harderian, lacrimal, submandibular,sublingual and parotid glands, and liver) were electrophoresedin an agarose gel and transferred to nylon membrane. The blotwas sequentially hybridized with unique 32P–labeled fragmentsof subcloned sequences. Actin was the positive control.Results:We identified four mouse secretoglobins, GenBank accession#'s AF008595, AF272844, AY370634 and AY370635. In an alignmentof AF008595 with androgen binding protein–alpha (XM_133375)of mouse salivary gland, the 5' and 3' untranslated regions(and the signal sequence) were more conserved (88% identity)than the protein coding region (72% identity). Likewise in analignment of AF272844, AY370634 and AY370635, the 5' and 3'untranslated regions (and the signal sequence) were more conserved(85% identity) than the protein coding region (65% identity).Among the tissues tested, sequence–specific labeled fragmentsof each secretoglobin clone hybridized only to the lacrimalgland RNA. Two of the secretoglobin clones (AF008595 and AY370634)hybridized equivalently to both male and female lacrimal glandRNA; two of the secretoglobin clones (AF272844 and AY370635)hybridized primarily to male mouse lacrimal gland RNA.Conclusions:Four mouse secretoglobin clones exhibited lacrimalgland–specific expression. Two of these were expressedprimarily in male mouse lacrimal gland. Higher sequence variabilitywithin the protein coding regions of these secretoglobin mRNAswould be consistent with an immunological function.